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Title: Nitric oxide detoxification by Fusarium verticillioides flavohemoglobin and role in pathogenicity of maize

item Baldwin, Thomas
item Glenn, Anthony - Tony

Submitted to: American Phytopathology Society
Publication Type: Abstract Only
Publication Acceptance Date: 8/12/2010
Publication Date: 8/12/2010
Citation: Baldwin, T.T., Glenn, A.E. 2010. Nitric oxide detoxification by Fusarium verticillioides flavohemoglobin and role in pathogenicity of maize. American Phytopathology Society. August 12, 2010. Nashville, TN.

Interpretive Summary: Abstract - no summary required.

Technical Abstract: Fusarium verticillioides is a non-obligate plant pathogen of maize causing a number of specific diseases, including root rot, kernel rot, seed rot, stalk rot, and seedling blight. The saprophytic nature of this fungus, its production of the mycotoxin fumonisin, and complex relationship maize puts this symbiont on the fence between a pathogen and a symptomless endophyte. One possible determinate of this lifestyle transition could be the complex regulation of Reactive Nitrogen Species (RNS) e.g. nitric oxide (NO) in the F. verticillioides – maize interaction. Recent articles have shown detoxification of NO to be necessary for the human pathogen Candida albicans and the plant pathogen Erwinia chrysanthemi in their pathogenicity. Both pathogens contain a flavohaemoglobin encoded by CaYHB1 and HmpX, respectively, and were shown to be responsible for this detoxification. A BLAST search of the Fusarium comparative genomes (Broad Institute) was conducted using these two genes revealed two hypothetical homologs in F. verticillioides, denoted NOD1 and NOD2 (Nitric Oxide Dioxygenase). To determine the functionality of the NOD1 and NOD2 homologous flavohaemoglobin genes, F. verticillioides knockouts were generated using homologous recombination and PEG mediated transformation. Inoculations of maize seedling with these knockouts were done to determine their pathogenic phenotypes. Other possible genes for regulation of NO in F. verticillioides were knocked out in F. verticillioides, including the gene for synthesis of NO.